The present invention relates to an improved action mechanism for pianos, in particular, upright pianos and
A piano playing technique called "repetition" is known in which, immediately after a hammer has struck a string following the depression of a piano key, the same piano key is depressed again before it completely returns to its original position, thereby producing the same tone.
This playing technique is utilized, for example, when the same tone is to be rapidly and continuously produced for a short period of time in a trill-like manner. If a grand piano is played using this technique, a complete form of repetition can be performed. This is facilitated by a known type of double escapement mechanism D and a known type of back check mechanism B which are typically incorporated in a conventional grand piano as shown in FIG. 5.
In general, in order to enable a rapidly repetitive striking of a piano string, it is necessary to employ a mechanism which acts according to the speed of depression of a piano key to return a hammer to predetermined position, which stops the return of the hammer at an intermediate position, or which limits the speed of return of the hammer utilizing the force of a spring or the like. The aforementioned escapement mechanism and back check mechanism are used to satisfy this requirement.
However, although a conventional type of upright piano may include the back check mechanism B as shown in FIG. 3, the double escapement mechanism D cannot be incorporated due to structional limitations.
It is to be noted that Japanese Utility Model Laid-open No. 108,496/1983 discloses an arrangement in which a double escapement mechanism is incorporated in an action mechanism of an upright piano.
The upright piano disclosed in this publication performs a function equivalent to that of an action mechanism for a grand piano in which, for example, as shown in FIG. 4, the depressing force applied to a piano key K is transmitted to a hammer H through the intermediary of a double escapement mechanism D of the type typically used in a grand piano. The disclosed upright piano further includes a type of back check mechanism B typically used in an upright piano as shown in FIG. 3.
However, as shown in FIG. 4, such an arrangement requires a relatively large second wippen 11a, as well as a first wippen 11. Although the back check mechanism B can move freely, the size of the escapement mechanism must significantly relatively small. It is thus impossible to obtain a satisfactory effect with this escapement mechanism, and the key touch quality inevitably suffers due to the weight and structure of the second wippen 11a. In addition, the presence of a tape T connecting the hammer H and a horizontal arm 12 may cause various problems. Therefore, the action structure shown in FIG. 4 has not yet been put to practical use.
Accordingly, although upright pianos may have various advantages such as their relatively small size, inexpensive price, and convenient operability, they are seldom used for public performances such as concerts. For this reason, some of students of the piano are finally forced to purchase a grand piano to practice on.
It is to be noted that the term "back check mechanism (B)" used herein is defined as a mechanism which can be incorporated in any grand piano or upright piano and in which, while a hammer is returning reactively after striking a string, the hammer is received at an intermediate position between the striking position and the rest position, thereby allowing a jack to positively strike the hammer at the succeeding depression of the same piano key.